1. Technical Field
The present invention relates to a voice over Internet protocol (referred to hereinafter as “VoIP”), and more particularly to a method for sending a dual-tone multi-frequency (i.e., “DTMF”) signal in a call connection state based on a VoIP.
2. Related Art
The Internet has recently been recognized as an essential communication medium to many persons. Using the Internet, persons can access a large number of sites providing information, goods and services, and rapidly communicate with those in all places over the whole world by means of electronic mails. With the spread of the Internet, a service has been proposed to provide voice communication between multimedia terminals, such as personal computers (PCs), and voice communication between a multimedia terminal and a conventional voice terminal, such as a telephone, over the Internet. This service is typically called a voice over Internet protocol (IP), or “VoIP”, and H.323 (standard for multimedia communication approved by the International Telecommunications Union) and standards associated therewith have been proposed for the VoIP.
The VoIP is adapted to support a multimedia terminal to send voice as well as data through the use of an Internet protocol, and has the advantage of significantly reducing line costs required for telephone or facsimile transmission, thereby enabling telephone users to receive a trunk call service and international call service under Internet and intranet environments by paying only local call fees. Moreover, the VoIP enables the management of voice traffic and data traffic by one equipment and circuit, thereby making it possible to utilize applications such as a Web call center, desktop video, etc.
On the other hand, a variety of attendant services, such as Internet paging, phone banking, electronic commerce, etc., are provided through a call connection, resulting in the necessitation of frequent inputs of numeral keys by a user in a call connection state. If the user inputs a numeral key, a calling telephone generates a dual-tone multi-frequency (i.e., “DTMF”) signal corresponding to the inputted numeral key, which is then sent to a called unit (for example, a paging terminal, phone banking center or so forth) over a data network (such as the Internet).
A DTMF signal, which is generated in response to the input of a numeral key by a caller in a call connection state based on the VoIP, is conventionally sent according to a real-time transport protocol (i.e., “RTP”) similarly to voice. As known, the RTP was developed to provide a function of transporting real-time data, such as voice, video or dummy data, on multicast or unicast.
However, because the RTP is a standard established on the basis of transfer characteristics of real-time data, it does not handle contents on resource reservation and, particularly, does not provide a flow control function such as timely delivery, QoS (Quality of Signal) assurance, out-of-order transfer prevention or the like. For this reason, it is impossible to sense a loss of data inputted by a caller during transfer thereof. In the regard, conventionally, a number inputted by a caller in a VoIP-based call connection state cannot be accurately transferred to a called party.
This application makes reference to, incorporates the same herein, from my application METHOD FOR SENDING DUAL-TONE MULTI-FREQUENCY SIGNAL USING VOICE OVER INTERNET PROTOCOL filed with the Korean Industrial Property Office on Dec. 9, 2000 and there duly assigned Serial No. 2000-74902.